It is named in honour of the British crystallographer Helen Dick Megaw (1 June 1907, Dublin, Ireland - 26 February 2002, Ballycastle, Northern Ireland) who made significant contributions to our understanding of the structure and properties of natural and synthetic perovskites. In 1989, Megaw became the first woman to receive the Roebling Medal of the Mineralogical Society of America.

Type Locality:

ⓘ Xenolith no. 3, Lakargi Mt., Upper Chegem volcanic caldera (Verkhnechegemskaya caldera), Baksan Valley, Kabardino-Balkaria, Russia

Isostructural with:

Perovskite

Perovskite Group. The Sn analogue of perovskite and lakargiite.
Chemically related to burtite.

Classification of MegawiteHide

IMA status:

Approved

Approval Year:

2010

Nickel-Strunz 10th (pending) ed.:

4.CC.30

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
C : Metal: Oxygen = 2: 3,3: 5, and similar
C : With large and medium-sized cations

Physical Properties of MegawiteHide

Lustre:

Vitreous

Transparency:

Transparent

Colour:

Pale yellowish brown, pale yellow to colourless

Streak:

White

Cleavage:

Distinct/Good
on {110} and {001}

Density:

5.06 g/cm³ (Calculated)

Optical Data of MegawiteHide

Type:

Biaxial

RI values:

n = 1.89

Max Birefringence:

δ = 0.000

Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.

Surface Relief:

Very High

Chemical Properties of MegawiteHide

Formula:

CaSnO₃

Elements listed:

Ca, O, Sn - search for minerals with similar chemistry

Crystallography of MegawiteHide

Crystal System:

Orthorhombic

Class (H-M):

mmm (2/m 2/m 2/m) - Dipyramidal

Space Group:

Pban

Cell Parameters:

a = 5.56(3) Å, b = 5.71(3) Å, c = 7.943(3) Å

Ratio:

a:b:c = 0.974 : 1 : 1.391

Unit Cell V:

252.17 Å³ (Calculated from Unit Cell)

X-Ray Powder DiffractionHide

Powder Diffraction Data:

d-spacing	Intensity
3.984	(52)
3.970	(19)
2.855	(43)
2.812	(100)
2.780	(19)
1.992	(13)
1.985	(13)
1.640	(13)

Type Occurrence of MegawiteHide

Type Locality:

ⓘ Xenolith no. 3, Lakargi Mt., Upper Chegem volcanic caldera (Verkhnechegemskaya caldera), Baksan Valley, Kabardino-Balkaria, Russia

General Appearance of Type Material:

Either pseudo-cubic or pseudo-cuboctahedral crystals do not exceed 15 µm in size and usually occur as inclusions in spurrite (xenolith No. 1). Megawite forms rims on µm-sized lakargiite crystals in larnite-cuspidine zones in skarns which contain abundant

Place of Conservation of Type Material:

Mineralogical Museum of Wrocław University, Poland under accession number MMUWrII16 717 and the Fersman Mineralogical Museum, Moscow, Russia under accession number4021/1.

Geological Setting of Type Material:

It was found in the spurrite zone of skarned xenolith no. 1 (20-25 m in size) in ignimbrite.

Associated Minerals at Type Locality:

Wadalite	Spurrite	Rondorfite	Periclase	Larnite
Lakargiite	Hydroxylellestadite	Grossular-Hibschite Series	Calcite

Synonyms of MegawiteHide

IMA2009-090

Relationship of Megawite to other SpeciesHide

Member of:

Perovskite Subgroup > Stoichiometric Perovskites Group > Perovskite Supergroup

Other Members of this group:

Barioperovskite	BaTiO₃	Orth. mm2 : Amm2
Goldschmidtite	KNbO₃	Iso. m3m (4/m 3 2/m) : Pm3m
Isolueshite	(Na,La)NbO₃	Iso. m3m (4/m 3 2/m) : Pm3m
Loparite-(Ce)	(Na,REE)Ti₂O₆
Lueshite	NaNbO₃	Orth. mmm (2/m 2/m 2/m)
Macedonite	PbTiO₃	Tet. 4/mmm (4/m 2/m 2/m) : P4/nmm
Perovskite	CaTiO₃	Orth. mmm (2/m 2/m 2/m) : Pnma
Tausonite	SrTiO₃	Iso. 4 3m

Related Minerals - Nickel-Strunz Grouping Hide

4.CC.	Allendeite	Sc₄Zr₃O₁₂	Trig. 3 : R3
4.CC.	Yttriaite-(Y)	Y₂O₃	Iso.
4.CC.05	Chrombismite	Bi₁₆CrO₂₇	Tet.
4.CC.10	Freudenbergite	Na₂(Ti,Fe)₈O₁₆	Mon.
4.CC.15	Grossite	CaAl₄O₇	Mon. 2/m : B2/b
4.CC.20	Chlormayenite	Ca₁₂Al₁₄O₃₂[◻₄Cl₂]	Iso. 4 3m : I4 3d
4.CC.25	Yafsoanite	Ca₃Zn₃(TeO₆)₂	Iso. m3 (2/m 3)
4.CC.30	Latrappite	Ca₂NbFe³⁺O₆	Orth. mmm (2/m 2/m 2/m) : Pnma
4.CC.30	Lueshite	NaNbO₃	Orth. mmm (2/m 2/m 2/m)
4.CC.30	Natroniobite	NaNbO₃	Mon.
4.CC.30	Perovskite	CaTiO₃	Orth. mmm (2/m 2/m 2/m) : Pnma
4.CC.30	Barioperovskite	BaTiO₃	Orth. mm2 : Amm2
4.CC.30	Lakargiite	Ca(Zr,Sn,Ti)O₃	Orth. mmm (2/m 2/m 2/m) : Pnma
4.CC.35	Loparite-(Ce)	(Na,REE)Ti₂O₆
4.CC.35	Macedonite	PbTiO₃	Tet. 4/mmm (4/m 2/m 2/m) : P4/nmm
4.CC.35	Tausonite	SrTiO₃	Iso. 4 3m
4.CC.35	Isolueshite	(Na,La)NbO₃	Iso. m3m (4/m 3 2/m) : Pm3m
4.CC.40	Crichtonite	Sr(Mn,Y,U)Fe₂(Ti,Fe,Cr,V)₁₈(O,OH)₃₈	Trig. 3 : R3
4.CC.40	Davidite-(Ce)	(Ce,La)(Y,U,Fe)(Ti,Fe)₂₀(O,OH)₃₈	Trig. 3 : R3
4.CC.40	Davidite-(La)	(La,Ce)(Y,U,Fe)(Ti,Fe)₂₀(O,OH)₃₈	Trig.
4.CC.40	Davidite-(Y)	(La,Ce,Na,Ca,Pb)(Y,Fe²⁺,◻)(Fe²⁺,Mn²⁺)₂(Ti,Fe³⁺,Nb,Zr)₁₈O₃₈ (hypothetical)	Trig.
4.CC.40	Landauite	NaMnZn₂(Ti,Fe)₆Ti₁₂O₃₈	Trig. 3 : R3
4.CC.40	Lindsleyite	(Ba,Sr)(Zr,Ca)(Fe,Mg)₂(Ti,Cr,Fe)₁₈O₃₈	Trig.
4.CC.40	Loveringite	(Ca,Ce,La)(Zr,Fe)(Mg,Fe)₂(Ti,Fe,Cr,Al)₁₈O₃₈	Trig.
4.CC.40	Mathiasite	(K, Ba, Sr)(Zr, Fe)(Mg,Fe)₂ (Ti,Cr,Fe)₁₈O₃₈	Trig.
4.CC.40	Senaite	Pb(Mn,Y,U)(Fe,Zn)₂(Ti,Fe,Cr,V)₁₈(O,OH)₃₈	Trig.
4.CC.40	Dessauite-(Y)	(Sr,Pb)(Y,U)(Ti,Fe³⁺)₂₀O₃₈	Trig. 3 : R3
4.CC.40	Cleusonite	(Pb,Sr)(U⁴⁺,U⁶⁺)(Fe²⁺,Zn)₂(Ti,Fe²⁺,Fe³⁺)₁₈(O,OH)₃₈	Trig. 3 : R3
4.CC.40	Gramaccioliite-(Y)	(Pb,Sr)(Y,Mn)Fe³⁺₂(Ti,Fe³⁺)₁₈O₃₈	Trig. 3
4.CC.45	Diaoyudaoite	NaAl₁₁O₁₇	Hex.
4.CC.45	Hawthorneite	BaMgTi₃Cr₄Fe²⁺₂Fe³⁺₂O₁₉	Hex. 6/mmm (6/m 2/m 2/m) : P6₃/mmc
4.CC.45	Hibonite	(Ca,Ce)(Al,Ti,Mg)₁₂O₁₉	Hex.
4.CC.45	Lindqvistite	Pb₂Mn²⁺Fe₁₆O₂₇	Hex.
4.CC.45	Magnetoplumbite	(Pb,Mn)(Fe,Mn)₁₂O₁₉	Hex.
4.CC.45	Plumboferrite	Pb₂(Fe³⁺,Mn²⁺,Mg)₁₁O₁₉	Trig. 3 2 : P3 1 2
4.CC.45	Yimengite	K(Cr,Ti,Fe,Mg)₁₂O₁₉	Hex.
4.CC.45	Haggertyite	BaFe²⁺₄Fe³⁺₂Ti₅MgO₁₉	Hex. 6/mmm (6/m 2/m 2/m) : P6₃/mmc
4.CC.45	Nežilovite	PbZn₂Mn⁴⁺₂Fe³⁺₈O₁₉	Hex. 6/mmm (6/m 2/m 2/m) : P6₃/mmc
4.CC.45	Batiferrite	BaTi₂Fe³⁺₈Fe²⁺₂O₁₉	Hex.
4.CC.45	Hibonite-(Fe)	(Fe,Mg)Al₁₂O₁₉	Hex. 6/mmm (6/m 2/m 2/m) : P6₃/mmc
4.CC.45	Barioferrite	BaFe³⁺₁₂O₁₉	Hex. 6/mmm (6/m 2/m 2/m) : P6₃/mmc
4.CC.50	Jeppeite	(K,Ba)₂(Ti,Fe)₆O₁₃	Mon.
4.CC.55	Zenzénite	Pb₃Fe₄Mn₃O₁₅	Hex.
4.CC.60	Mengxianminite (of Huang et al.)	(Ca,Na)₃(Fe,Mn)₂Mg₂(Sn,Zn)₅Al₈O₂₉

Other InformationHide

Health Risks:

No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for MegawiteHide

Reference List:

Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)

Galuskin, E.V., Galuskina, I.O., Gazeev, V.M., Dzierżanowski, P., Prusik, K., Pertsev, N.N., Zadov, A.E. & Gurbanov, A.G. (2010): Megawite CaSnO3 - a new mineral of the perowskite group. 20th General Meeting of the IMA (IMA2010), Budapest, Hungary, August 21-27, CD of Abstracts, p. 444.

Galuskin, E.V., Galuskina, I.O., Gazeev, V.M., Dzierżanowski, P., Prusik, K., Pertsev, N.N., Zadov, A.E., Bailau, R. & Gurbanov, A.G. (2011): Megawite, CaSnO3: a new perovskite-group mineral from skarns of the Upper Chegem caldera, Kabardino-Balkaria, Northern Caucasus, Russia. Mineralogical Magazine, 75, 2563-2572.

Internet Links for MegawiteHide

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https://www.mindat.org/min-39893.html
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External Links:

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Raman and XRD data at RRUFF project

References and PDF downloads at RRUFF project

American Mineralogist Crystal Structure Database

Handbook of Mineralogy page PDF

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Localities for MegawiteHide

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the

symbol to view information about a locality. The

symbol next to localities in the list can be used to jump to that position on the map.

Locality ListHide

- This locality has map coordinates listed.

- This locality has estimated coordinates. ⓘ - Click for further information on this occurrence. ? - Indicates mineral may be doubtful at this locality.

- Good crystals or important locality for species.

- World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). ~~Struck out~~ - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.

Russia (TL)

Kabardino-Balkaria

Baksan Valley

Upper Chegem volcanic caldera (Verkhnechegemskaya caldera)

Lakargi Mt.

ⓘ Xenolith no. 3 (TL)

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Megawite

About MegawiteHide